The invention concerns an outlet nozzle for centrifuge drums, consisting of a nozzle holder with an axial intake channel and with an orifice that is made of a harder material, that fits into the channel, and that has an axial outlet channel comprising a cylindrical bore downstream of an entry cone, whereby the orifice is positioned in the nozzle holder such that the axis of symmetry of the intake channel is at an angle to that of the outlet channel, diverting the flow of the fluid through the nozzle.
A nozzle of this type is known from U.S. Pat. No. 2 695 748. It is appropriate for both radial installation at the circumference of the drum and axial installation at its top or bottom. Some of the energy consumed can be recovered in such a system by orienting the outlet channel at an angle to the intake channel. The outlet nozzle is inserted into the drum such that the fluid leaving outlet channel will leave the nozzle in a direction opposite the direction that the drum is rotating in.
The entry cone in the orifice of the known outlet nozzles is designed to ensure that the inner surface facing the intake channel and with the cone extending from it will force the fluid flowing through the intake channel to change direction before it can arrive in the cone.
That damage, especially due to cavitation and erosion, can frequently occur to the nozzle holder in outlet nozzles of this genus is known. Such damage can lead not only to rapid failure of the nozzle but also, if it is replaced too late, to damage to the centrifuge drum itself.
Extensive investigations have demonstrated that the aforesaid phenomena of cavitation and erosion originate at the interface between the rear of the orifice and the surface of the intake channel, specifically in the section of the intake channel near the outlet channel.